The recent detection of gravitational waves from coalescing binary black holes by LIGO allowed for the first time the direct observation of stellar-mass black holes. These gravitational wave detections, complemented by a 45-year-long history of indirect observations of black holes in X-ray binaries, can give us now a more complete picture of the formation and evolution of binary stellar systems containing black holes. Yet, to date, a number of physical processes involved in the formation and evolution of these systems remain poorly understood. In this talk, after briefly reviewing our current understanding of the evolutionary channels leading to the formation of black-hole binary, I will discuss the some of the main uncertainties involved in these formation scenarios: the occurrence of natal kicks during the core-collapse phase leading to black-hole formation, the angular momentum content of the formed black holes and the phase of dynamically unstable mass-transfer also known as common envelope. Finally, I will present an outlook of how we can improve, in the near future, our understanding in all these fronts.